Formation of chlorinated hydrocarbons during combustion of poly (vinyl chloride)

Pilot-scale experiments were carried out to study the formation of chlorinated hydrocarbons through combustion of PVC. Vinyl chloride, dichloro-, trichloro-, tetrachloro-, pentachloro-, and hexachlorobenzenes were determined by GC/ECD. Furthermore, some peaks in the chromatogram were tentatively assigned to octachlorostyrene and PCB. The total amount of lipophilic organochlorinated compounds was determined by neutron activation analysis. The results indicate that incineration of PVC is not a major source of chlorinated hydrocarbons in the environment.     

Comparative health impact assessment of local and regional particulate air pollutants in Scandinavia

The ongoing program Clean Air for Europe (CAFE) is an initiative from the EU Commission to establish a coordinated effort to reach better air quality in the EU. The focus is on particulate matter as it has been shown to have large impact on human health. CAFE requested that WHO make a review of the latest findings on air pollutants and health to facilitate assessments of the different air pollutants and their health effects. The WHO review project on health aspects of air pollution in Europe confirmed that exposure to particulate matter (PM), despite the lower levels we face today, still poses a significant risk to human health. Using the recommended uniform risk coefficients for health impact assessment of PM, regardless of sources, premature mortality related to long-range transported anthropogenic particles has been estimated to be about 3500 deaths per year for the Swedish population, corresponding to a reduction in life expectancy of up to about seven months. The influence of local sources is more difficult to estimate due to large uncertainties when linking available risk coefficients to exposure data, but the estimates indicate about 1800 deaths brought forward each year with a life expectancy reduction of about 2-3 months. However, some sectors of the population are exposed to quite high locally induced concentrations and are likely to suffer excessive reductions in life expectancy. Since the literature increasingly supports assumptions that combustion related particles are associated with higher relative risks, further studies may shift the focus for abatement strategies. CAFE sets out to establish a general cost effective abatement strategy for atmospheric particles. Our results, based on studies of background exposure, show that long-range transported sulfate rich particles dominate the health effects of PM in Sweden. The same results would be found for the whole of Scandinavia and many countries influenced by transboundary air pollution. However, several health studies, including epidemiological studies with a finer spatial resolution, indicate that engine exhaust particles are more damaging to health than other particles. These contradictory findings must be understood and source specific risk estimates have to be established by expert bodies, otherwise it will not be possible to find the most cost effective abatement strategy for Europe. We are not happy with today's situation where every strategy to reduce PM concentrations is estimated to have the same impact per unit change in the mass concentration. Obviously there is a striking need to introduce more specific exposure variables and a higher geographical resolution in epidemiology as well as in health impact assessments.     

Molecular Weight Changes and Polymeric Matrix Changes Correlated with the Formation of Degradation Products in Biodegraded Polyethylene

The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products. The samples were thermooxidized for 6 days at 100°C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.     

An Experiment with Forced Oxygenation of the Deepwater of the Anoxic By Fjord,Western Sweden

In a 2.5-year-long environmental engineering experiment in the By Fjord, surface water was pumped into the deepwater where the frequency of deepwater renewals increased by a factor of 10. During the experiment, the deepwater became long-term oxic, and nitrate became the dominating dissolved inorganic nitrogen component. The amount of phosphate in the water column decreased by a factor of 5 due to the increase in flushing and reduction in the leakage of phosphate from the sediments when the sediment surface became oxidized. Oxygenation of the sediments did not increase the leakage of toxic metals and organic pollutants. The bacterial community was the first to show changes after the oxygenation, with aerobic bacteria also thriving in the deepwater. The earlier azoic deepwater bottom sediments were colonized by animals. No structural difference between the phytoplankton communities in the By Fjord and the adjacent Havsten Fjord, with oxygenated deepwater, could be detected during the experiment.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0524-9) contains supplementary material, which is available to authorized users.     

On the preconditions for large-scale collective action

Ambio - The phenomenon of collective action and the origin of collective action problems have been extensively and systematically studied in the social sciences. Yet, while we have substantial...     

瑞典水文变化-气候变化影响模拟

温室效应加剧导致的气候变化将会引起水文系统的变化.随着气候要素的变化,水文变化将会在全球呈现出区域差异性.因此,有必要开展局地和区域尺度上的水文变化影响研究,评价不同区域将会受到怎样的影响.本研究旨在对广泛的瑞典流域上气候变化的水文影响(响应)进行评估.我们采用不同的方法,将气候模型中产生的气候变化信号转换输入到水文模型中.利用瑞典区域气候模拟计划(SWECLIM)生成的区域气候情景,我们进行了几次水文模型模拟研究.得出的基本结论是根据流域的地理位置处于瑞典北部或南部,气候变化对河道水流的分区影响是显著不同的.此外,预测的水文变化不仅与用于确定区域气候模型边界条件的全球气候模型的选择有关,而且与人为气体排放情景的选取有关.     

Biofidelity Corridors for Sternum Kinematics in Low-Speed Side Impacts

Objective: Field data show that side impact car crashes have become responsible for a greater proportion of the fatal crashes compared to frontal crashes, which suggests that the protection gained in frontal impact has not been matched in side impact. One of the reasons is the lack of understanding of the torso injury mechanisms in side impact. In particular, the deformation of the rib cage and how it affects the mechanical loading of the individual ribs have yet to be established. Therefore, the objective of this study was to characterize the ribcage deformation in side impacts by describing the kinematics of the sternum relative to the spine.

Methods: The 3D kinematics of the 1st and of the 5th or 6th thoracic vertebrae and of the sternum were obtained for three Post Mortem Human Subjects (PMHS) impacted laterally by a rigid wall traveling at 15 km/h. The experimental data were processed to express the kinematics of the sternum relative to the spine throughout the impact event. Methods were developed to interpolate the kinematics of the vertebrae for which experimental data were not available.

Results: The kinematics of the sternocostal junction for ribs 1 to 6 as well as the orientation of the sternum were expressed in the vertebra coordinate systems defined for each upper thoracic vertebra (T1 to T6). Corridors were designed for the motion of the sternum relative to each vertebra. In the experiments, the sternum moved upward for all rib levels (1 to 6), and away from the spine with an amplitude that increased with the decreasing rib level (from rib 1 to rib 6). None of the differences observed in the kinematics could be correlated to the occurrence of rib fractures.

Conclusions: This study provides both qualitative and quantitative information for the ribcage skeletal kinematics in side impact. This data set provides the information required to better evaluate computational models of the thorax for side impact simulations. The corridors developed in this study provide new biofidelity targets for the impact response of the ribcage. This study contributes to augmenting the state of knowledge of the human chest deformation in side impact to better characterize the rib fracture mechanisms.     

Assessment of Bilateral Thoracic Loading on the Near-Side Occupant Due to Occupant-to-Occupant Interaction in Vehicle Crash Tests

Objective: This study aims, by means of the WorldSID 50th percentile male, to evaluate thoracic loading and injury risk to the near-side occupant due to occupant-to-occupant interaction in combination with loading from an intruding structure.

Method: Nine vehicle crash tests were performed with a 50th percentile WorldSID male dummy in the near-side (adjacent to the intruding structure) seat and a THOR or ES2 dummy in the far-side (opposite the intruding structure) seat. The near-side seated WorldSID was equipped with 6 + 6 IR-Traccs (LH and RH) in the thorax/abdomen enabling measurement of bilateral deflection. To differentiate deflection caused by the intrusion, and the deflection caused by the neighboring occupant, time history curves were analyzed. The crash tests were performed with different modern vehicles, equipped with thorax side airbags and inflatable curtains, ranging from a compact car to a large sedan, and in different loading conditions such as car-to-car, barrier, and pole tests. Lateral delta V based on vehicle tunnel acceleration and maximum residual intrusion at occupant position were used as a measurement of crash severity to compare injury measurements.

Result: In the 9 vehicle crash tests, thoracic loading, induced by the intruding structure as well as from the far-side occupant, varied due to the size and structural performance of the car as well as the severity of the crash. Peak deflection on the thoracic outboard side occurred during the first 50 ms of the event. Between 70 to 150 ms loading induced by the neighboring occupant occurred and resulted in an inboard-side peak deflection and viscous criterion. In the tests where the target vehicle lateral delta V was below 30 km/h and intrusion less than 200 mm, deflections were low on both the outboard (20–40 mm) and inboard side (10–15 mm). At higher crash severities, delta V 35 km/h and above as well as intrusions larger than 350 mm, the inboard deflections (caused by interaction to the far-side occupant) were of the same magnitude or even higher (30–70 mm) than the outboard deflections (30–50 mm).

Conclusion: A WorldSID 50th percentile male equipped with bilateral IR-Traccs can detect loading to the thorax from a neighboring occupant making injury risk assessment feasible for this type of loading. At crash severities resulting in a delta V above 35 km/h and intrusions larger than 350 mm, both the inboard deflection and VC resulted in high risks of Abbreviated Injury Scale (AIS) 3+ injury, especially for a senior occupant.     

Combustion experiments using pentachlorophenol on a pilot scale and full-scale

Chlorinated phenols are used at many saw mills for impregnation of saw timber. Waste products containing the used compound follow this process. Tests have been performed on pilot and full-scale in order to investigate the possibility of destroying these wastes by combustion.The pilot scale tests with 70 g of pentachlorophenol show that at a transit time of approximately 3 seconds and a combustion temperature of 600°C the unburnt residue was 50 mg/kg fed in pentachlorophenol. At 800°C the residue decreased to 15 mg/kg. No formation of octachlorodioxin could be proved.The full-scale test with a small amount of pentachlorophenol and a large amount of tetrachlorophenol show that at a transit time of approximately 0.9 seconds and a temperature varying during one test between 620–875° (average 760°C), the unburnt residue was 9 mg/kg for tetrachlorophenol and 650 mg/kg for pentachlorophenol. At an increased load the residue increased gradually, being 5.900 mg/kg for tetrachlorophenol and 7.100 mg/kg for pentachlorophenol at a test when the temperature was varied between 460 and 850° (average 620°C). Analyses of chlorinated dioxins show that octachlorodioxin was found in the flue gas at one of the tests. This may indicate a formation.